1. Field of the Invention
The present invention relates to a technology for improving a credibility of operating a cold start device in a fuel injection pump for a diesel engine equipped with the cold start device.
2. Background Art
Conventionally, there are well-known fuel injection pumps for diesel engines, comprising a plunger, a plunger barrel, wherein the plunger is vertically reciprocated in the plunger barrel so as to send pressurized fuel to the distribution shaft, the distribution shaft delivers it to a plurality of delivery valves, and the respective delivery valves send the fuel to fuel injection nozzles.
Some of the well-known fuel injection pumps include cold start devices (“Cold Start Device”, hereinafter, referred to as “CSD”), wherein an overflowing sub-port is formed and a sparking actuator is operated by a controller, thereby opening and closing the overflowing sub-port so as to change an injection timing.
Due to the CSD, when started up in a low temperature, a starting performance of an engine is improved by closing the sub-port so as to accelerate the injection timing, i.e., by performing a sparking control. The overflowing sub-port is a port so as to communicate a fuel pressure chamber with a hypobaric chamber (a low pressure oil passage). The coupling and decoupling of the fuel pressure chamber with the hypobaric chamber are performed by operating the CSD piston interposed between both chambers with the sparking actuator and the like.
However, the CSD is not operated during the summer seasons because it makes it a rule to operate only when started up in a low temperature during the winter seasons and the like, thereby causing a possibility of fixing the CSD piston with the sliding surface of the piston barrel due to the deterioration of the fuel and the like. That is to say, when the CSD is operated for a long time, there is a problem of detracting a credibility of operating the CSD piston.
Therefore, as disclosed in JP 2004-316486, the credibility of operating the CSD piston is improved by operating the CSD with the arbitrary manipulation of the operator even if started up in a low temperature.
However, it is preferable not only to operate the CSD but also to confirm a fault of it in a warm temperature so as to improve the credibility of operating the fuel injection pump.
Also, the CSD sometimes exerts a harmful influence on the diesel engine by arbitrarily operating it because the operation of it affects the amount of fuel consumption. For example, an excessive amount of fuel consumption when starting up the diesel engine causes a black smoke degeneration.
Accordingly, the problem so as to be solved is to confirm the fault of the CSD in order to improve the credibility of the fuel injection pump without affecting the amount of fuel consumption.